The NIAID/DAIT Adjuvant Development Program supports the development of new candidate vaccine adjuvants that stimulate innate immune responses to protect against infection by NIAID Category A, B, and C Pathogens. Currently, aluminum hydroxide/aluminum phosphate (alum) is the only licensed adjuvant for general human use in the United States. Because alum is not a universally effective adjuvant, additional adjuvants are sought that can stimulate more broadly effective and safe responses to a wide variety of microorganisms. Candidate vaccine adjuvants eligible for support must: 1) be previously identified and characterized as safe, 2) function by activating the innate immune system, 3) have a documented mechanism of action for the adjuvant, 4) be part of a Product Development Plan that will significantly advance the product within the 5 year period of contract performance, and 5) when possible, be able to augment vaccine efficacy safely against an NIAID Category A, B, and C Pathogen upon pathogenic challenge in an in vivo animal model.